Fuel pump dome structure



Jan. 29, 1957 l. E. COFFEY 2,779,353

FUEL PUMP DOME'STRUCTURE Filed Oct. 29. 1952 s Sheets-Sheet 1 INVENTOR. F IRVEN E. COFFEY ATTORNEY Jan. 29, 1957 I. E. COFFEY 2,779,353

FUEL PUMP DOME STRUCTURE Filed Oct. 29, 1952 5 Sheets-Sheet 2 INVENTOR. IRVEN E. COFFEY ATTORNEY Jan. 29, 1957 E. COFFEY 2,779,353

FUEL PUMP DOME STRUCTURE Filed Oct. 29, 1952 3 Sheets-Sheet 3 INVENTOR,

FUEL PUMP DOME STRUCTURE Irven E. Cotiey,.Clayton, Mo., assignor, bymesne assignments, to ACF Industries, Incorporated, New York, N. Y., a corporation of New Jersey Application Gctoher 29, 1952, Serial No. 317,498

4 Claims. (Cl. 138-26) This invention relates generally to reciprocating fuel pumps for internal combustion engines, and the like, and more specifically to means incorporatedin said pumps to eliminate the pulsations inv the flow to and from the pump. It is well understood that the action of an air dome will eliminate pulsations andaccomplish this desired result, but it is also well understood that fuel pumps must be capable of operation in any pump position. and that, accordingly, a simple air dome structure is not satisfactory.

As the art along this line developed, it became common practice to provide fuel pumps with pulsator chambers in direct communication with each of the valves. The pulsator chamber furnished the air dome eifect by using a resilient diaphragm enclosing a column of air, and thus permanently separating the fluid pumped from the fluid in the air dome. This served the desired purpose of providing a permanent pulsator in all pump positions, but restricted the action of the air dome by the resistance inherent in the necessary stretching of the rubber diaphragm due to pulsations tending to compress or expand the fluid in the air dome.

The present invention relates to pulsator chambers, in which a novel diaphragm is employed of a design which does not restrict the full cushioningaction of the air column itself. Thus, the diaphragm is preshaped so that it will collapse readily under the influence of pumping pulsations, and thereby provide maximum air dome capacity. The resistance of the diaphragm to forces tending to compress or collapse the diaphragm is supplied by the column of air sealed Within, and not primarily by the stretching of the plastic diaphragm enclosure forming the air dome. This same inherent characteristic offlexing is also provided in the opposite sense, in which the cushioning is provided by expansion of the column of air within the plastic enclosure forming the air dome, but this expansion is resisted beyond limited designed displacements by the resilience of the plastic enclosure or diaphragm.

The object of the invention is to provide an improved pulsator chamber for a reciprocating type of fuel pump.

Another objectof the invention is to provide a diaphragm shape for apulsator which provides for air'dome resistance producedmostly by the air instead of by the resilience of the diaphragm.

Other objects of the invention Will become apparent as the description proceeds.

Referring to the drawingsz Fig. 1 is a side sectional elevatio-nal view of a fuel pump construction illustrating the present invention.

Fig. 2 is a top plan view'of the-valve casing with the diaphragm and covers removed to show the location of the valve seats.

Fig. 3 is a plan view of the hat-shaped diaphragm used in the pump shown in Fig. 1.

Fig. 4 is a view in section along line 4-4 of the diaphragm shown in Fig. 3.

nited States Patent ice Fig. 5 is an end view in section along line 5-5 of the diaphragm of Fig. 4.

Fig. 6. is a fragmented view in section through the pulsator chamber for the outlet valve of the pump of Fig. 1 illustrating the diaphragm shown in Fig. 3 collapsed under pump discharge pressure.

Fig. 7 is a top plan view of another form of valve casing usable in. the pump shown in Pig. 1.

Fig. 8 is a top plan view of a hat-shaped diaphragm adapted for use in Fig. 7.

Fig. 9 is a View in section along line 9-9 of thediaphragm of Fig. 8.

Fig. 10 is a top plan view of a modified form of'hau section diaphragm usable in Fig. 7.

Fig. llis a view in section along line ll-11 of Fig. 10.

Pg. 12 is a top plan view of a fuel pump showing. a modifiedform of pulsator chamber on the intake side.

Fig. 13 is. a front elevation in section along line 13-13.

of the pump shown in Fig. 1.2.

In Fig. 1 is shown a hat-section typeof pump, so called because of the shape of the diaphragm forming the enclosure for the air dome.

The pump illustrated in Fig. I has a body portion 1, which is a metal die casting, usually of aluminum alloy, or the like. The body portion is divided into two sections, the upper part forming a valve casing 2 shown in plan view in Fig. 2, and the lower part a levercasing 3. The casings are joined together by a serie of screws 4. through flanges 5 and 6 on the valve casing and lever casing, respectively. in the valve casing are two vertically extending hollow chambers 7 and 8 provided with integral threaded bosses at 9 and it! for the intake and outa let connections from the pump. The valve casing 2 also. includes the pump chamber generally indicated a 11, and between the pump chamber and the hollow chambers 7 and ii are bridging members having two series of ports .14 and 15 under control of the intake and outlet valve assemblies 16 and 17, respectively.

The upper end of each of chambers 7 and 3 is rabbeted to receive and seat hat-shaped diaphragms 19 and 20, .and each is, in turn, sealed by a welsh plug 21 and 22 seated on the rims of the diaphragms, respectively, and wedgingly engaged in the rabbets provided at the upper ends of the respective chambers.

The lever casing 3 mounts an oscillating lever 25 on a pin 26 within the flange 27. Flange 27 is provided with means for attachment to the engine positioned so that the arm 25 will be rocked by the cam 23 on the camshaft 29 of the engine in one direction, and by a spring 30 between the casing and the lever in the opposite: direction. Lever 25 connects with a stem 32 for directly actuating a diaphragm 33 within the pump chamber 11. Surrounding the stem 32 is a compression spring Bid for securing the usual oil seals 35 in the casing 3 seated on a shoulder 36 therein. The diaphragm 33 is attached to the stem 32 by a series of washers between shoulder 37 and a headed over-portion of the stern in the usual manner.

Turning now to Figs. 3 to 5, a detailed description of the diaphragm follows:

The diaphragms l9 and 2t) are identical, and, since each must fit within the oval chambers 7 and 8, the diaphragms are of complementary shape. A description of one will sufiice for all. 1

The hat-shaped diaphragm of Figs. 3 to 5 has a nar row rim it? formed with a half-round shape on its inner face as shown in it, and with a planar surface on its outer face 42. The purpose of the bead il is to prevent the diaphragm from being drawn out of the rabbeted portion provided in the top of the chamber. The rim 40 surrounds a crown 43, which extends downwardly into th e chambers. This crown is pre-shaped with a crease 44 extending in the direction of its major axis which allows the crown to be crushed inwardly under compression produced by the pump, or to flex downwardly in response to suction. Outside of the fact that this major axis is much too long for the width, the diaphragm has a striking resemblance to a mans fedora hat with a very narrow brim, and this shape lends itself to be readily collapsible under pressure, as illustrated in Fig. 6. When collapsed by compression of the pump, the crease 44 folds until the sides of the crown meet, and this involve no stretching as in prior diaphragms, but merely sufiicient resilience to allow the diaphragm to bend. Although hot illustrated, the suction of the pump produces the reverse effect on the hat section, and the crease 44 will be eliminated. Thus the air dome, and not the diaphragm, supplies practically the entire cushioning effect. The diaphragm itself is not ordinarily stretched, but, of course, it is constructed of plastic, so that it can stretch if sufficient pressure differential between the air dome and chamber exists to increase the air dome displacement beyond designed limits.

In Fig. 7, a modified form of valve casing 2 is shown with the diaphragms and seals removed. Since the pump structure otherwise is identical with that shown in Fig. 1, illustration in detail is not deemed necessary.

Fig. 7 utilizes valve chambers which are cylindrical rather than oval, and, for this reason, different hat-section diaphragms are required. In Figs. 8 and 9 one such hatsection diaphragm is shown suitable for use in the cylindrical valve chambers '7' and 8' shown in Fig. 7. The hat-section of Figs. 8 and 9 has a narrow brim t provided with a planar portion 51 for contact by the welch plug to seal the diaphragm within the valve chamber 7' or 8', as the case may be. The crown 5'2 is generally round, and its upper side is corrugated by circular groove 53 and indentation 54, generally concentrically arranged. These corrugations provide the same sort of action as illustrated in Fig. 6 for the other type of hat-section. The crown 52 may be crushed or collapsed in a very similar manner.

In Figs. 10 and 11 is shown an alternative form of hatsection diaphragm having a narrow rim 57 and a planar surface 58 for contact with the welch plug to seal the joint between the diaphragm and the valve chamber 7 or 8' as the case may be. The crown 59 is generally triangular in shape and provided with an indentation 69, which allows the crown to be crushed in all directions under the compression produced by the pump, or, on the other hand, to be flexed downwardly in response to suetion. In this respect its action resembles that of the hatsections shown by the previous figures.

Fig. 12 shows a modified form of the pump shown in Fig. 1, and, since the structures are substantially identical, like reference characters are applied to indicate like parts. The description of these views will be limited to details which differ from those shown in Fig. 1. In this modification, the outlet valve chamber 7 is the same as that shown in Fig. 1. The inlet chamber 8", however, has no diaphragm, but is provided with means for trapping a column of air regardless of pump position. In Fig. 12 this means is clearly illustrated as a partition '79 which surrounds each of the valves in turn and is provided with an opening communicating directly with the intake connection 9. The partition '79 forms a chamber which extends upwardly about two thirds of the way within the valve chamber $5". When the pump is in an upright position, as shown in Fig. 13, a column of air will be trapped above the valve in the zone above the inlet connection 9, whereas, if the pump is inverted, a column of air will be trapped in the zone 71 surrounding partition 70.

A series of modifications has been described which will carry out the objects of the invention as above set forth. It is contemplated that other combinations and configurations which represent equivalents of the structure disclosed are possible, and those illustrated, therefore, should be regarded for the purpose of example only.

I claim:

1. A pulsator device for attachment to a duct for pulsating fluid pressure comprising means forming a gasfilled closed chamber and including a diaphragm sealing said chamber from said duct, said diaphragm having a crease formed therein defining a fold line to permit collapse of the walls of the diaphragm at the crease without stretching or compressing the Walls of the diaphragm during folding and unfolding, whereby slight pulsations from the'duct may be transmitted to the gas charge in said chamber without substantial resistance due to stretching or compression of the diaphragm.

2. A pulsator device for attachment to a duct for pulsating fluid comprising means forming a gas-filled closed chamber and including .a resilient pre-shaped diaphragm of pliable material sealing said chamber from said duct, said diaphragm having a crease formed therein defining a fold line to permit collapse of the walls of the diaphragm at the crease without stretching or compressing the walls of the diaphragm during folding and unfolding, whereby slight pulsations from the duct may be transmitted to the ga charge in said chamber without substantial resistance due to stretching or compression of the diaphragm.

3. A pulsator device for attachment to a duct for pulsating fluid pressure comprising means forming a gasfilled closed chamber and including a resilient pre-shaped diaphragm of pliable material sealing said chamber from said duct, said diaphragm having a crease formed therein defining a. fold line to permit collapse of the walls of the diaphragm at the crease without stretching or compressing the walls of the diaphragm during folding and unfolding, whereby slight pulsations from the duct may be transmitted to the gas charge in said chamber, without substantial resistance due to stretching or compression fo the diaphragm, said diaphragm being generally cup-shaped to provide a side wall and a crown.

4. A pulsator device for attachment to a duct for pulsating fluid pressure comprising means forming a gasfilled closed chamber and including a resilient pro-shaped diaphragm of pliable material sealing said chamber from said duct, said diaphragm having a crease formed therein defining a fold line to permit collapse of the walls of the diaphragm at the crease without stretching or compressing the walls of the diaphragm during folding and unfolding, whereby slight pulsations from the duct may be transmitted to the gas charge in said chamber without substantial resistance due to stretching or compression of the diaphragm, said diaphragm being generally cup-shaped to provide a side wall and a crown, said crease being formed in said crown.

References Cited in the file of this patent UNITED STATES PATENTS 1,796,126 Smith Mar. 10, 1931 1,944,340 Zubaty et a1. Jan. 23, 1935 2,106,791 Brisson Feb. 1, 1938 2,276,568 Erickson Mar. 17, 1942 2,287,841 Tabb June 30, 1942 2,3(l8,04l Babitch et al Jan. 12, 1943 2,465,274 Rudd Mar. 22, 1949 2,697,448 Gates Dec. 21, 1954 2,697,449 Svcnson Dec. 21, 1954 

